/*
 *   Copyright 2008 Francois Fernandes
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */
package com.googlecode.opendoclibrary.internal.impl.fs.meta;

import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Map.Entry;

import com.googlecode.opendoclibrary.library.spi.IMetadataEntry;

final class MetadataIterator implements Iterator<IMetadataEntry>
{

    private Iterator<Map.Entry<String, String>> current;

    private String currentPrefix;

    private Iterator<Map.Entry<String, Map<String, String>>> mapIter;

    /**
     * @param metadata
     */
    public MetadataIterator( Map<String, Map<String, String>> data )
    {
        mapIter = data.entrySet().iterator();
    }

    @Override
    public boolean hasNext()
    {
        updateActiveIterator();
        return current != null && current.hasNext();
    }

    @Override
    public IMetadataEntry next()
    {
        updateActiveIterator();
        if ( current == null )
        {
            throw new NoSuchElementException();
        }
        Entry<String, String> e = current.next();

        return new MetadataEntry( currentPrefix, e.getKey(), e.getValue() );
    }

    @Override
    public void remove()
    {
        throw new UnsupportedOperationException();
    }

    private void updateActiveIterator()
    {
        if ( current == null || !current.hasNext() )
        {
            current = null;
            currentPrefix = null;
            if ( mapIter.hasNext() )
            {
                Entry<String, Map<String, String>> nextMap = mapIter.next();
                currentPrefix = nextMap.getKey();
                current = nextMap.getValue().entrySet().iterator();
                // invoke recursive as we may have a empty map
                updateActiveIterator();
            }
        }

    }
}